A wireless device, a first network node and methods therein

ABSTRACT

A wireless device ( 120 ) and method for performing cell configuration. The wireless device and a first network node ( 111 ) serving the wireless device are operating in a wireless communications network ( 100 ), wherein the first network node manages a first serving cell ( 111   a ). When the wireless device is to send a second Random Access (RA) transmission in the first serving cell to the first network node while preparing to perform or performing configuration of a second serving cell managed by a second network node, the wireless device configures the second serving cell using a configuration time delay T act   _   PSCell  comprising at least a time delay T RA   _   PCell  due to the second RA transmission, otherwise the wireless device configures the second serving cell using the configuration time delay T act   _   PSCell  excluding the time delay T RA   _   PCell  due to the second RA transmission.

TECHNICAL FIELD

Embodiments herein relate to a wireless device, a first network node andmethods therein. Especially, embodiments herein relate to performingcell configuration.

BACKGROUND

Communication devices such as terminals or wireless devices are alsoknown as e.g. User Equipments (UE), mobile terminals, wireless terminalsand/or mobile stations. Such terminals are enabled to communicatewirelessly in a wireless communication system or a cellularcommunications network, sometimes also referred to as a cellular radiosystem or cellular networks. The communication may be performed e.g.between two terminals, between a terminal and a regular telephone and/orbetween a terminal and a server via a Radio Access Network (RAN) andpossibly one or more core networks, comprised within the cellularcommunications network.

The above terminals or wireless devices may further be referred to asmobile telephones, cellular telephones, laptops, or tablets withwireless capability, just to mention some further examples. Theterminals or wireless devices in the present context may be, forexample, portable, pocket-storable, hand-held, computer-comprised, orvehicle-mounted mobile devices, enabled to communicate voice and/ordata, via the RAN, with another entity, such as another terminal or aserver.

The cellular communications network covers a geographical area which isdivided into cell areas, wherein each cell area being served by anaccess node such as a base station, e.g. a Radio Base Station (RBS),which sometimes may be referred to as e.g. “eNB”, “eNodeB”, “NodeB”, “Bnode”, or BTS (Base Transceiver Station), depending on the technologyand terminology used. The base stations may be of different classes suchas e.g. macro eNodeB, home eNodeB or pico base station, based ontransmission power and thereby also cell size. A cell is thegeographical area where radio coverage is provided by the base stationat a base station site. One base station, situated at the base stationsite, may serve one or several cells. Further, each base station maysupport one or several communication technologies. The base stationscommunicate over the air interface operating on radio frequencies withthe terminals or wireless devices within range of the base stations. Inthe context of this disclosure, the expression Downlink (DL) is used forthe transmission path from the base station to the mobile station. Theexpression Uplink (UL) is used for the transmission path in the oppositedirection i.e. from the mobile station to the base station.

In 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE),base stations, which may be referred to as eNodeBs or even eNBs, may bedirectly connected to one or more core networks.

3GPP LTE radio access standard has been written in order to support highbitrates and low latency both for uplink and downlink traffic. All datatransmission is in LTE controlled by the radio base station.

LTE uses Orthogonal Frequency-Division Multiplexing (OFDM) in thedownlink and Discrete Fourier Transform (DFT)-spread OFDM in the uplink.The basic LTE downlink physical resource can thus be seen as atime-frequency grid as schematically illustrated in FIG. 1, where eachresource element corresponds to one OFDM subcarrier during one OFDMsymbol interval.

In the time domain, LTE downlink transmissions are organized into radioframes of 10 ms, each radio frame consisting of ten equally-sizedsubframes of length T_(subframe)=1 ms, cf. FIG. 2.

Furthermore, the resource allocation in LTE is typically described interms of Resource Blocks (RB), where a resource block corresponds to oneslot, e.g. 0.5 ms, in the time domain and 12 contiguous subcarriers inthe frequency domain. A pair of two adjacent resource blocks in timedirection, e.g. 1.0 ms, is known as a resource block pair. Resourceblocks are numbered in the frequency domain, starting with 0 from oneend of the system bandwidth.

The notion of Virtual Resource Blocks (VRB) and Physical Resource Blocks(PRB) has been introduced in LTE. The actual resource allocation to aterminal, e.g. a UE, is made in terms of VRB pairs. There are two typesof resource allocations, e.g. localized resource allocation anddistributed resource allocation. In the localized resource allocation, aVRB pair is directly mapped to a PRB pair, hence two consecutive andlocalized VRB are also placed as consecutive PRBs in the frequencydomain. On the other hand, the distributed VRBs are not mapped toconsecutive PRBs in the frequency domain; thereby providing frequencydiversity for data channel transmitted using these distributed VRBs.

Downlink transmissions are dynamically scheduled, i.e., in each subframethe base station transmits control information about to which terminalsdata is transmitted and upon which resource blocks the data istransmitted, in the current downlink subframe. This control signaling istypically transmitted in the first 1, 2, 3 or 4 OFDM symbols in eachsubframe and the number n=1, 2, 3 or 4 is known as the Control FormatIndicator (CFI) indicated by the Physical CFI CHannel (PCHICH)transmitted in the first symbol of the control region. The controlregion also comprises Physical Downlink Control CHannels (PDCCH) andpossibly also Physical Hybrid Automatic Repeat Request (HARQ) IndicationCHannels (PHICH) carrying ACK/NACK for the uplink transmission.

The downlink subframe also comprises Common Reference Symbols (CRS),which are known to the receiver and used for coherent demodulation ofe.g. the control information. A downlink system with CFI=3 OFDM symbolsas control is illustrated in FIG. 3.

Random Access

In LTE, as in any communication system, a mobile terminal, e.g. a UE orwireless device, may need to contact the network, e.g. via the eNodeB,without having a dedicated resource in the Uplink (UL), i.e. from UE tobase station. To handle this, a random access procedure is availablewhere a UE that does not have a dedicated UL resource may transmit asignal to the base station. The first message of this procedure istypically transmitted on a special resource reserved for random access,e.g. on a Physical Random Access CHannel (PRACH). This channel can forinstance be limited in time and/or frequency (as in LTE). See FIG. 4.

The resources available for PRACH transmission is provided to theterminals as part of the broadcasted system information in SystemInformation Block 2 (SIB-2) or as part of dedicated RRC signaling incase of e.g. handover.

The resources consist of a preamble sequence and a time and/or frequencyresource. In each cell, there are 64 preamble sequences available. Twosubsets of the 64 sequences are defined, where the set of sequences ineach subset is signaled as part of the system information. Whenperforming a contention-based random-access attempt, the terminalselects at random one sequence in one of the subsets. As long as noother terminal is performing a random-access attempt using the samesequence at the same time instant, no collisions will occur and theattempt will, with a high likelihood, be detected by the base station,e.g. the eNodeB.

In LTE, the random access procedure may be used for a number ofdifferent reasons. Among these reasons are

-   -   Initial access for e.g. UEs in the RRC_IDLE state;    -   Incoming handover;    -   Resynchronization of the UL e.g. UE inactivity after long DRX        cycle, e.g. 640 ms, UE transmission after long inactivity, e.g.        after 500 ms;    -   Scheduling request for e.g. a UE that is not allocated any other        resource for contacting the base station;    -   Positioning e.g. for UE performing UE Rx-Tx time difference        measurement, for enabling eNode B to perform eNode B Rx-Tx time        difference measurement, timing advance etc.;

The contention-based random access procedure used in LTE Rel-10 isillustrated in FIG. 5 involving a UE and an LTE RAN comprising a basestation e.g. an eNode B (eNB) communicating with the UE. The UE startsthe random access procedure by randomly selecting one of the preamblesavailable for contention-based random access. The UE then transmits theselected random access preamble on the Physical Random Access CHannel(PRACH) to the base station, e.g. the eNode B (eNB), in the RAN.

The RAN, e.g. the base station, acknowledges any preamble it detects bytransmitting a random access response (MSG2) including an initial grantto be used on the uplink shared channel, a Temporary C-RNTI (TC-RNTI),and a Time Alignment (TA) update based on the timing offset of thepreamble measured by the eNodeB on the PRACH. The MSG2 is transmitted inthe DL to the UE using the PDSCH and its corresponding PDCCH messagethat schedules the PDSCH contains a Cyclic Redundancy Check (CRC) whichis scrambled with the RA-RNTI.

When receiving the response from the RAN the UE uses the grant totransmit a message (MSG3) that in part is used to trigger theestablishment of radio resource control and in part to uniquely identifythe UE on the common channels of the cell. The timing alignment commandprovided in the random access response is applied in the UL transmissionin MSG3.

In addition, the base station, e.g. the eNB, may also change theresources blocks that are assigned for a MSG3 transmission by sending anUL grant to the UE that has its CRC scrambled with the TC-RNTI which wasincluded in MSG2. In this case the PDCCH is used, to transmit the DCIcontaining the uplink grant.

The RAN, e.g. the base station, sends a contention resolution message tothe UE in MSG4. The MSG4, which is then contention resolving, has itsPDCCH CRC scrambled with the C-RNTI if the UE previously has a C-RNTIassigned. If the UE does not have a C-RNTI previously assigned, the MSG4has its PDCCH CRC scrambled with the TC-RNTI obtained from MSG2.

The procedure ends with the RAN, e.g. the base station, solving anypreamble contention that may have occurred for the case that multipleUEs transmitted the same preamble at the same time. This can occur sinceeach UE randomly selects when to transmit and which preamble to use. Ifmultiple UEs select the same preamble for the transmission on RACH,there will be contention between these UEs that needs to be resolvedthrough the contention resolution message (MSG4). The case whencontention occurs is illustrated in FIG. 6, where two UEs denoted UE₁and UE₂ transmit the same preamble p₅ at the same time. A third UEdenoted UE₃ also transmits at the same RACH, but since it transmits witha different preamble p₁ there is no contention between this UE UE₃ andthe other two UEs UE₁ and UE₂.

The UE can also perform non-contention based random access. Anon-contention based random access or contention free random access cane.g. be initiated by the base station, e.g. the eNB, to get the UE toachieve synchronisation in UL. The eNB initiates a non-contention basedrandom access either by sending a PDCCH order or indicating it in an RRCmessage. The latter of the two is used in case of handover (HO).

The procedure for the UE to perform contention free random access isillustrated in FIG. 7 involving a UE and an LTE RAN comprising a basestation e.g. an eNode B (eNB) communicating with the UE. Similar to thecontention based random access schematically illustrated in FIG. 5, theMSG2 is transmitted in the DL to the UE and its corresponding PDCCHmessage CRC is scrambled with the RA-RNTI. The UE considers thecontention resolution successfully completed after it has received MSG2successfully.

For the contention free random access as for the contention based randomaccess does the MSG2 contain a timing alignment value. This enables theeNB to set the initial/updated timing according to the UEs transmittedpreamble.

Dual Connectivity

A dual connectivity framework is currently being considered for LTERel-12. Dual Connectivity refers to the operation where a given UEconsumes radio resources provided by at least two different networkpoints, e.g. by a Master eNB (MeNB), sometimes herein also referred toas a Main eNB, and a Secondary eNB (SeNB) connected with non-idealbackhaul while in RRC_CONNECTED mode. By the expression non-idealbackhaul when used herein is meant that exchange of messages between theMeNB and SeNB involves at least some delay e.g. 10 ms or more. A UE indual connectivity maintains simultaneous connections to anchor andbooster nodes, where the MeNB is interchangeably called anchor node andthe SeNB is interchangeably called booster node. As the name implies,the MeNB controls the connection and handover of SeNB. No SeNBstandalone handover is defined for Rel-12. Signaling in MeNB is neededeven in SeNB change. Both the anchor node and booster node may terminatethe control plane connection towards the UE and may thus be thecontrolling nodes of the UE.

The UE reads system information from the anchor node. In addition to theanchor node, the UE may be connected to one or several booster nodes foradded user plane support. The MeNB and SeNB are connected via the Xninterface, which is currently selected to be the same as the X2interface between two eNBs.

More specifically Dual Connectivity (DC) is a mode of operation of a UEin RRC_CONNECTED state, where the UE is configured with a Master or MainCell Group (MCG) and a Secondary Cell Group (SCG). Cell Group (CG) is agroup of serving cells associated with either the MeNB or the SeNB. TheMCG and SCG are defined as follows:

-   -   Master or Main Cell Group (MCG) is a group of serving cells        associated with the MeNB, comprising a primary cell, PCell and        optionally one or more secondary cells, SCells.    -   Secondary Cell Group (SCG) is a group of serving cells        associated with the SeNB comprising of pSCell (Primary Scell)        and optionally one or more SCells.

Master eNB is the eNB which terminates at least S1-MME. Secondary eNB isthe eNB that is providing additional radio resources for the UE but isnot the Master eNB.

FIG. 8 describes dual connectivity setup. In this example, only one SeNBis connected to the UE, however, more than one SeNB may serve the UE ingeneral. As shown in the figure, it is also clear that dual connectivityis a UE specific feature and a network node may support a dual connectedUE and a legacy UE at the same time.

As mentioned earlier, the anchor and booster roles for any specific nodeare defined from a UE point of view. This means that a node that acts asan anchor node to one UE may act as booster node to another UE.Similarly, though the UE reads the system information from the anchornode, a node acting as a booster node to one UE, may or may notdistribute system information to another UE.

In this disclosure, anchor node and MeNB are used with interchangeablemeaning, and similarly, SeNB and booster node are also usedinterchangeably herein.

MeNB:

-   -   Provides system information    -   Terminates control plane    -   May terminate user plane

SeNB:

-   -   May terminate control plane    -   Terminates only user plane

In one application, dual connectivity allows a UE to be connected to twonetwork nodes to receive data from both nodes to increase its data rate.This user plane aggregation achieves similar benefits as CarrierAggregation (CA) using network nodes that are not connected bylow-latency backhaul connection and/or network connection. Due to thislack of low-latency backhaul, the scheduling and HARQ-ACK feedback fromthe UE to each of the nodes will need to be performed separately. Thatis, it is expected that the UE may have two UL transmitters to transmitUL control and data to the connected nodes.

Synchronized or Unsynchronized Dual Connectivity Operation

Since dual connectivity operation involves two non-co-locatedtransmitters, i.e. MeNB and SeNB, one issue related to UE receiverperformance is the maximum receive timing difference Δt of the signalsfrom MeNB and SeNB received at the UE receiver. This gives rise to twocases of DC operation with respect to the UE: synchronized DC operationand unsynchronized DC operation.

-   -   The synchronized DC operation herein means that the UE may        perform DC operation provided the received time difference Δt        between the signals received at the UE from the CCs belonging to        the MCG and SCG are within a certain threshold e.g. ±33 μs.    -   The unsynchronized DC operation herein means that the UE may        perform DC operation regardless of the received time difference        Δt between the signals received at the UE from the CCs belonging        to the MCG and SCG i.e. for any value of Δt up to 500 μs.

Maximum receive timing difference Δt at the UE consists of thecomponents, namely:

-   -   (1) Relative propagation delay difference between MeNB and SeNB,    -   (2) Tx timing difference due to synchronization levels between        antenna connectors of MeNB and SeNB, and    -   (3) Delay due to multipath propagation of radio signals

SCell Activation/Deactivation Procedure

In dual connectivity the UE will be connected to two eNodeBssimultaneously; MeNB and SeNB. Each of them may have one or moreassociated SCells which may be configured for DL, or DL and UL CAoperation. The SCells are time-aligned to the MeNB and SeNB,respectively, but the MeNB and SeNB may or may not be time aligned withrespect to their frame timings and/or their respective System FrameNumber (SFN).

MeNB can only activate and deactivate serving cells, e.g. SCells,associated with MeNB. SeNB can only activate and deactivate servingcells, e.g. SCells, associated with SeNB. Cross-eNB activation and/ordeactivation is not supported.

The configuration and simultaneous activation, as well as release (hencedeactivation), of Special SCell belonging to SeNB is done by MeNB, andhence that the above mentioned agreement shall only refer to SCellsassociated with MCG and SCG, respectively. Hence, for example, the MeNBconfigures and activates the Special SCell but not any of the ordinarySCells in the SCG. Similarly the MeNB deactivates and releases theSpecial SCell but not any of the ordinary SCells in the SCG.

For configuration and simultaneous implicit activation of Special SCellit shall be noted that the activation time may be considerable longerthan currently assumed for legacy CA. The fact that the Special SCellgoes directly into activated state upon configuration means that the UEmight not have had a chance to identify it before the activation, hencethe activation might be blind. The UE will also have to acquire SFNtiming difference to MeNB by reading MIB from the Special SCell as partof the activation procedure, for purpose of aligning e.g. DRX cycleoffset and measurement gap offset between MeNB and SeNB. Acquiring SFNadds maximum an extra 50 ms to the activation time both for regular andblind activation of the Special SCell.

For legacy CA, i.e. CA without dual connectivity, the SCell activationtimes are 24 and 34 ms for regular and blind activation, respectively;3GPP TS 36.133 section 7.7, Release 10 (Rel-10). For those numbers toapply it is assumed that the SCell has already been configured by thenetwork via RRC Connection Reconfiguration message (3GPP TS 36.331section 5.3.5, Rel-10) when the MAC control element activating the cellis received (3GPP TS 36.321 section 5.13, Rel-10). Hence forsimultaneous configuration and activation also the RRC procedure delayneeds to be taken into account—often 15 ms is assumed for such delay.

Blind activation in legacy CA can make use of that it is known that themaximum time difference between any two cells being aggregated shall bewithin 30.26 ms (3GPP TS 36.300 annex J.1). Hence the UE only has toassume that the cell to be detected is misaligned by at most half anOFDM symbol, which significantly improves and speeds up the celldetection. In case of unsynchronized MeNB and SeNB both with respect toSFN and frame timing, the UE cannot make such assumption, and the celldetection will be similar to cell detection time for blind handover,which under favourable signal conditions is specified to 80 ms (3GPP TS36.133 section 5.1).

SUMMARY

In dual connectivity involving two primary cells serving a UE, the UE,e.g. the wireless device, may need to send PRACH to both the primarycells, e.g. the primary cell (PCell) and the primary secondary cell(PSCell), in MeNB and SeNB, simultaneously. As will be described below,sometimes herein, the MeNB is referred to as a first network node, theSeNB is referred to as a second network node, the PCell is referred toas a first serving cell and the PSCell is referred to as a secondserving cell. The UE may send PRACH to the PSCell for initialconfiguration and/or activation. Since the UE may be power limited,therefore any attempt to transmit the two PRACH to the PCell and thePSCell in MeNB and SeNB, respectively, will disrupt the dualconnectivity operation. Embodiments herein address this problem anddevise solutions to solve this problem.

Further, the configuration and/or activation of PSCell in dualconnectively is completed when the UE sends Random Access (RA) to thePSCell. However, in the prior art, during or at the start of suchprocedure the UE may also have to send another RA to the PCell. Anattempt to perform simultaneous RA transmissions to the PSCell and thePCell may prevent the UE to correctly execute the configuration and/oractivation of the PSCell. Also any attempt to perform simultaneous RAtransmissions to the PSCell and the PCell may also disrupt the procedurerelated to the PCell e.g. handover, positioning measurement etc. Inexisting solution there is no mechanism to address this problem.

Therefore, an object of embodiments herein is to overcome theabove-mentioned drawbacks among others and to improve the performance ina wireless communications network.

According to a first aspect of embodiments herein, the object isachieved by a method performed by a wireless device for performing cellconfiguration. The wireless device and a first network node serving thewireless device are operating in a wireless communications network,wherein the first network node manages a first serving cell.

When the wireless device is to send a second Random Access (RA)transmission in the first serving cell to the first network node whilepreparing to perform or performing configuration of a second servingcell managed by a second network node, the wireless device configuresthe second serving cell using a configuration time delay T_(act) _(_)_(PSCell) comprising at least a time delay T_(RA) _(_) _(PCell) due tothe second RA transmission, otherwise the wireless device configures thesecond serving cell using the configuration time delay T_(act) _(_)_(PSCell) excluding the time delay T_(RA) _(_) _(PCell) due to thesecond RA transmission.

According to a second aspect of embodiments herein, the object isachieved by a wireless device for performing cell configuration. Thewireless device and a first network node serving the wireless device areoperable in a wireless communications network. The first network nodemanages a first serving cell.

When the wireless device is to send a second Random Access (RA)transmission in the first serving cell to the first network node whilepreparing to perform or performing configuration of a second servingcell managed by a second network node, the wireless device is configuredto configure the second serving cell using a configuration time delayT_(act) _(_) _(PSCell) comprising at least a time delay T_(RA) _(_)_(PCell) due to the second RA transmission, otherwise the wirelessdevice is configured to configure the second serving cell using theconfiguration time delay T_(act) _(_) _(PSCell) excluding the time delayT_(RA) _(_) _(PCell) due to the second RA transmission.

According to a third aspect of embodiments herein, the object isachieved by a method performed by a first network node for assisting awireless device in performing cell configuration. The wireless deviceand the first network node serving the wireless device are operable in awireless communications network. The first network node manages a firstserving cell.

The first network node determines based on one or more criteria whetherthe wireless device is using or is expected to use a first method or asecond method for performing configuration of a second serving cellmanaged by a second network node.

The first method is configured to be performed over a configuration timedelay T_(act) _(_) _(PSCell) comprising at least a time delay T_(RA)_(_) _(PCell) due to a second Random Access (RA) transmission, when thewireless device is to send the second RA transmission in the firstserving cell to the first network node while preparing to perform orperforming configuration of the second serving cell.

The second method is configured to be performed over the configurationtime delay T_(RA) _(_) _(PSCell) excluding the time delay T_(RA) _(_)_(PCell) due to the second RA transmission, when the wireless device isnot to send the second RA transmission in the first serving cell whilepreparing to perform or performing configuration of the second servingcell.

Further the first network node transmits, to the wireless device,information relating to the determined first or second method.

According to a fourth aspect of embodiments herein, the object isachieved by a first network node for assisting a wireless device inperforming cell configuration, wherein the wireless device and the firstnetwork node serving the wireless device are operating in a wirelesscommunications network. The first network node manages a first servingcell.

The first network node is configured to determine based on one or morecriteria whether the wireless device is using or is expected to use afirst method or a second method for performing configuration of a secondserving cell managed by a second network node.

The first method is configured to be performed over a configuration timedelay T_(act) _(_) _(PSCell) comprising at least a time delay T_(RA)_(_) _(PCell) due to a second Random Access (RA) transmission, when thewireless device is to send the second RA transmission in the firstserving cell to the first network node while preparing to perform orperforming configuration of the second serving cell.

The second method is configured to be performed over the configurationtime delay T_(act) _(_) _(PSCell) excluding the time delay T_(RA) _(_)_(PCell) due to the second RA transmission, when the wireless device isnot to send the second RA transmission in the first serving cell whilepreparing to perform or performing configuration of the second servingcell.

Further, the first network node is configured to transmit, to thewireless device, information relating to the determined first or secondmethod.

According to a fifth aspect of embodiments herein, the object isachieved by a computer program, comprising instructions which, whenexecuted on at least one processor, causes the at least one processor tocarry out the method performed by the wireless device.

According to a sixth aspect of embodiments herein, the object isachieved by a computer program, comprising instructions which, whenexecuted on at least one processor, causes the at least one processor tocarry out the method performed by the first network node.

According to a seventh aspect of embodiments herein, the object isachieved by a carrier comprising the computer program, wherein thecarrier is one of an electronic signal, an optical signal, a radiosignal or a computer readable storage medium.

Since the wireless device configures the second serving cell using aconfiguration time delay T_(act) _(_) _(PSCell) comprising at least atime delay T_(RA) _(_) _(PCell) due to the second RA transmission, whenthe wireless device is to send the second RA transmission in the firstserving cell to the first network node while preparing to perform orperforming configuration of a second serving cell managed by a secondnetwork node, and since the wireless device configures the secondserving cell using the configuration time delay T_(act) _(_) _(PSCell)excluding the time delay T_(RA) _(_) _(PCell) due to the second RAtransmission, when the wireless device is not to send the second RAtransmission in the first serving cell to the first network node whilepreparing to perform or performing configuration of the second servingcell, the wireless device consumes less power without interrupting thedual connectivity operation or ongoing procedures, such as handoverand/or positioning measurement relating to the serving cell. Thisresults in an improved performance in the wireless communicationsnetwork.

An advantage with embodiments herein is thus that the dual connectivityoperation and other ongoing procedures, such as handover and/orpositioning measurement relating to the serving cell, will not beinterrupted.

Another advantage is that the wireless device may perform PSCellconfiguration and/or activation procedure, i.e. the configuration of thesecond serving cell, without discarding random access to the firstserving cell (PCell).

A further advantage is that the wireless device is enabled to send RA tothe first serving cell under critical situation, e.g. positioningmeasurements for emergency call, etc., by adaptively delaying the PSCellconfiguration and/or activation procedure.

A yet further advantage is that the wireless device is enabled to adaptthe PSCell configuration and/or activation procedure in response tosimultaneous transmissions of RA to the PCell, e.g. the first servingcell, and the at least one PSCell, e.g. the second serving cell.

BRIEF DESCRIPTION OF DRAWINGS

Examples of embodiments herein will be described in more detail withreference to attached drawings in which:

FIG. 1 schematically illustrates an LTE downlink physical resource;

FIG. 2 schematically illustrates an LTE time-domain structure;

FIG. 3 schematically illustrates a downlink subframe;

FIG. 4 schematically illustrates a random-access-preamble transmission;

FIG. 5 is a signalling diagram that schematically illustrates acontention-based random access procedure;

FIG. 6 schematically illustrates a wireless communications network withcontention between two UEs;

FIG. 7 is a signalling diagram that schematically illustrates acontention-free random access procedure;

FIG. 8 schematically illustrates a wireless communications networkcomprising dual connectivity deployment;

FIG. 9 schematically illustrates an embodiment of a wirelesscommunications network;

FIG. 10 is a flowchart depicting embodiments of a method performed by awireless device;

FIG. 11 is a flowchart depicting embodiments of a method performed by awireless device;

FIG. 12 is a schematic block diagram illustrating embodiments of awireless device;

FIG. 13 is a flowchart depicting embodiments of a method performed by anetwork node; and

FIG. 14 is a schematic block diagram illustrating embodiments of anetwork node.

DETAILED DESCRIPTION Terminologies

The following commonly terminologies are used in embodiments describedherein and are elaborated below:

Network node: In some embodiments a more general term “network node” isused and it may correspond to any type of radio network node or anynetwork node, which communicates with a UE and/or with another networknode. Examples of network nodes are NodeB, MeNB, SeNB, a network nodebelonging to MCG or SCG, Base Station (BS), multi-Standard Radio (MSR)radio node such as MSR BS, eNodeB, network controller, radio NetworkController (RNC), Base Station Controller (BSC), relay, donor nodecontrolling relay, Base Transceiver Station (BTS), Access Point (AP),transmission points, transmission nodes, Radio Remote Unit (RRU), RemoteRadio Head (RRH), nodes in Distributed Antenna System (DAS), corenetwork node (e.g. Mobile Switching Center (MSC), Mobility ManagementEntity (MME) etc), Operations and Maintenance (O&M), Operations SupportSystem (OSS), Self-organizing Network (SON), positioning node (e.g.Enhanced Serving Mobile Location Center (E-SMLC)), Mobile Data Terminal(MDT) etc.

User equipment/wireless device: In some embodiments the non-limitingterms wireless device and User Equipment (UE) are used and they refer toany type of wireless device communicating with a network node and/orwith another UE in a cellular or mobile communication system. Examplesof UE/wireless device are target device, Device-to-Device (D2D) UE,machine type UE or UE capable of machine to machine (M2M) communication,Personal Digital Assistant (PDA), iPAD, Tablet, mobile terminals, smartphone, Laptop Embedded Equipped (LEE), Laptop Mounted Equipment (LME),Universal Serial Bus (USB) dongles etc. In this disclosure the termswireless device and UE are used interchangeably

General

Note that although terminology from 3GPP LTE has been used in thisdisclosure to exemplify embodiments, this should not be seen as limitingthe scope of the invention to only the aforementioned system. Otherwireless systems, including Wideband Code Division Multiple Access(WCDMA), High Speed Packet Access (HSPA), Worldwide Interoperability forMicrowave Access (WiMax), WiFi, Wireless Local Area Network (WLAN), andGlobal System for Mobile Communications (GSM)/GSM EDGE Radio AccessNetwork (GERAN), may also benefit from exploiting the ideas coveredwithin this disclosure.

Also note that terminology such as eNodeB and UE should be consideringnon-limiting and does in particular not imply a certain hierarchicalrelation between the two; in general “eNodeB” could be considered asdevice 1 and “UE” device 2, and these two devices communicate with eachother over some radio channel. Further, the description frequentlyrefers to wireless transmissions in the downlink, but embodiments hereinare equally applicable in the uplink.

The embodiments are described in the context of single carrier operationof the UE. However, the embodiments are applicable for multi-carrier orcarrier aggregation operation of the UE. Therefore, the embodimentmethods of signaling information to the UE or to the other network nodemay be carried out independently for each cell on each carrier frequencysupported by the network node.

In this disclosure, MeNB and SeNB refer to two different network nodes,as previously described.

In the following section, embodiments herein will be illustrated in moredetail by a number of exemplary embodiments. It should be noted thatthese embodiments are not mutually exclusive. Components from oneembodiment may be tacitly assumed to be present in another embodimentand it will be obvious to a person skilled in the art how thosecomponents may be used in the other exemplary embodiments.

FIG. 9 depicts an example of a wireless communications network 100 inwhich embodiments herein may be implemented. The wireless communicationsnetwork 100 is a wireless communication network such as an LTE, WCDMA,GSM network, any 3GPP cellular network, Wimax, or any cellular networkor system.

The wireless communications network 100 comprises a plurality of networknodes whereof a first network node 111 and a second network node 112 aredepicted in FIG. 9. The first network node 111 and the second networknode 112 may each be a transmission point such as a radio base station,for example an eNB, an eNodeB, or a Home Node B, an Home eNode B or anyother network node capable to serve a user equipment or a machine typecommunication device in a wireless communications network.

In this description, the first network node 111 is sometimes referred toas a Master or Main eNB (MeNB), or as an anchor node. Thus, the termsfirst network node, MeNB and anchor node are used interchangeably.

Further, in this description, the second network node 112 is sometimesreferred to as a Secondary eNB (SeNB) or as a booster node. Thus, theterms second network node, SeNB and booster node are usedinterchangeably.

The first network node 111 is configured for wireless communication withone or more wireless devices, such as a wireless, when located within ageographical area, e.g. a first serving cell 111 a, served by the firstnetwork node 111. Herein, this is also specified as the first networknode 111 manages or is configured to manage the first serving cell 111a. In this description, the first serving cell 111 a is sometimesreferred to as a Primary Cell (PCell). Thus, the terms first servingcell and PCell are used interchangeably herein.

The second network node 112 is configured for wireless communicationwith one or more wireless devices, such as the wireless device 120, whenlocated within a geographical area, e.g. a second serving cell 112 a,served by the second network node 112. Herein, this is also specified asthe second network node 112 manages or is configured to manage thesecond serving cell 112 a. In this description, the second serving cell112 a is sometimes referred to as a Primary Secondary Cell (PSCell).Thus, the terms second serving cell and PSCell are used interchangeablyherein.

The wireless device 120 also referred to as a user equipment or UE islocated in the wireless communication network 100. The first wirelessdevice 120 may e.g. be a user equipment, a mobile terminal or a wirelessterminal, a mobile phone, a computer such as e.g. a laptop, a PersonalDigital Assistants (PDAs) or a tablet computer, sometimes referred to asa surf plate, with wireless capability, or any other radio network unitscapable to communicate over a radio link in a wireless communicationsnetwork. It should be noted that the term user equipment used in thisdocument also covers other wireless devices such as Machine to machine(M2M) devices, even though they are not handled by any user.

Embodiments described herein comprises a number of actions that may beperformed at the network node side, e.g. at the first network node 111,and the UE side, e.g. at the wireless device 120. For example, whileconfiguring and/or activating a PSCell in SeNB: if the UE is notrequired to send RA on the PCell in MeNB then the UE uses a first methodto configure and/or activate the PSCell, but if the UE is also requiredto send RA on the PCell in the MeNB then UE uses a second method toconfigure and/or activate the PSCell. In other words, while configuringand/or activating the second serving cell 112 a at the second networknode 112, if the wireless device 120 is not required to send RA on thefirst serving cell 111 a in the first network node 111 then the wirelessdevice 120 uses a first method to configure and/or activate the secondserving cell 112 a, but if the wireless device 120 is also required tosend RA on the first serving cell in the first network node then thewireless device 120 uses a second method to configure and/or activatethe second serving cell 112 a.

One or more of the following actions may be performed in a UE, e.g. thewireless device 120, configured to operate in Dual Connectivity (DC):

-   -   Determining whether the UE, e.g. the wireless device 120, is        triggered or has received a request to send a second Random        Access (RA) transmission while the UE, e.g. the wireless device        120, is preparing to perform or is performing configuration        and/or activation of at least one primary secondary cell        (PSCell), e.g. the second serving cell 112 a, said second random        access transmission is used for sending RA to a primary cell        (PCell), e.g. the first serving cell 111 a, and said PSCell and        PCell are primary serving cells belonging to Master Cell Group        (MCG) and Secondary Cell Group (SCG), respectively, in DC        operation;    -   Adapting or selecting between at least a first method and a        second method to configure and/or activate at least one PSCell,        e.g. the second serving cell 112 a, depending upon the        determination that whether or not the UE, e.g. the wireless        device 120, has been triggered or received the request to send        the second RA;    -   Configuring and/or activating at least one PSCell, e.g. the        second serving cell 112 a, based on the adapted method.

One or more of the following actions may be performed in a network node,e.g. the first network node 111, communicating with a UE, e.g. thewireless device 120, configured to operate in dual connectivity (DC):

-   -   Determining based on one or more criteria out of at least a        first method and a second method for use by a UE, e.g. the        wireless device 120, to configure and/or activate at least one        PSCell, e.g. the second serving cell 112 a;    -   Transmitting to the UE, e.g. the wireless device 120,        information related to the determined method and/or at least one        parameter related to the to the determined method.

An example of a method performed by the wireless device 120 forperforming cell configuration will now be described with reference to aflowchart depicted in FIG. 10. The wireless device 120 and the firstnetwork node 111 serving the wireless device 120 are operating in thewireless communications network 100, and the first network node 111manages the first serving cell 111 a.

The methods comprise one or more of the following actions. It should beunderstood that these actions may be taken in any suitable order andthat some actions may be combined.

Action 1001

The wireless device 120 may determine whether it is required to send asecond Random Access (RA) transmission in the first serving cell 111 ato the first network node 111 while performing configuration of thesecond serving cell 112 a.

The RA transmission in the first serving cell 111 a to the first networknode 111 is herein referred to as the second RA transmission since thewireless device 120 while performing configuration of the second servingcell 112 a has or is to send a RA transmission in the second servingcell 112 a to the second network node 112 which RA transmission hereinis referred to as a first RA transmission. However, it should beunderstood that the first RA transmission may be referred to as thesecond RA transmission and vice versa.

Action 1002

In some embodiments, when the wireless device 120 has determined whetherthe wireless device 120 is required to send the second RA transmissionin the first serving cell 111 a to the first network node 111 whileperforming configuration of the second serving cell 112 a as mentionedin Action 1001 above, the wireless device 120 selects between includingand excluding the time delay T_(RA) _(_) _(PCell) due to the second RAtransmission in the total time delay T_(act) _(_) _(PSCell) based on thedetermination.

When used herein, the expression “including and excluding the time delayT_(RA) _(_) _(PCell) in the configuration time delay T_(act) _(_)_(PSCell)” should be understood as whether or not the time delay T_(RA)_(_) _(PCell) is to be comprised in the configuration time delay T_(act)_(_) _(PSCell). It should be understood that irrespective of whether ornot the time delay T_(RA) _(_) _(PCell) is comprised in theconfiguration time delay T_(act) _(_) _(PSCell), the configuration timedelay T_(act) _(_) _(PSCell) may comprise one or more other time delays.

In some embodiments, the wireless device 120 selects between includingand excluding the time delay T_(RA) _(_) _(PCell) due to the second RAtransmission by further selecting to exclude the time delay T_(RA) _(_)_(PCell) due to the second RA transmission when the wireless device 120is not required to send the second RA transmission to the first networknode 111 while the wireless device 120 is preparing to perform or isperforming configuration of the second serving cell 112 a.

Alternatively, in some embodiments, the wireless device 120 selectsbetween including and excluding the time delay T_(RA) _(_) _(PCell) dueto the second RA transmission by further selecting to include the timedelay T_(RA) _(_) _(PCell) due to the second RA transmission when thewireless device 120 is to send the second RA transmission to the firstnetwork node 111 while the wireless device 120 is preparing to performor is performing configuration of the second serving cell 112 a.

Action 1003

When the wireless device 120 is to send the second RA transmission inthe first serving cell 111 a to the first network node 111 whilepreparing to perform or performing configuration of a second servingcell 112 a managed by a second network node 112, the wireless device 120configures the second serving cell 112 a using a configuration timedelay T_(act) _(_) _(PSCell) comprising at least a time delay T_(RA)_(_) _(PCell) due to the second RA transmission; otherwise the wirelessdevice 120 configures the second serving cell 112 a using theconfiguration time delay T_(act) _(_) _(PSCell) excluding the time delayT_(RA) _(_) _(PCell) due to the second RA transmission.

Thus, the wireless device 120 may configure the second serving cell 112a based on the selection described under Action 1002 above.

The expression “second RA on PCell in MeNB” is sometimes used herein forthe second RA transmission sent from the wireless device 120 in thefirst serving cell 111 a to the first network node 111.

In some embodiments. the configuration delay T_(act) _(_) _(PSCell)further comprises a time delay T_(RA) _(_) _(PSCell) due to a first RAtransmission in the second serving cell 112 a managed by the secondnetwork node 112.

In some embodiments, when the wireless device 120 selects to exclude thetime delay T_(RA) _(_) _(PCell) due to the second RA transmission, theconfiguration time delay T_(act) _(_) _(PSCell) is expressed as:

T _(act) _(_) _(PSCell) =α+T _(RRC) +T _(act) +T _(SFNacq) +T _(RA) _(_)_(PSCell),

wherein α is a margin parameter, T_(RRC) is a time delay due to a RadioResource Control (RRC) procedure, T_(act) is a time delay due to asecond serving cell activation procedure, T_(SFNacq) is a time delay dueto a System Frame Number (SFN) acquisition procedure and T_(act) _(_)_(PSCell) is a time delay due to a first RA transmission in the secondserving cell 112 a managed by the second network node 112.

Alternatively, in some embodiments, when the wireless device 120 selectsto include the time delay T_(RA) _(_) _(PCell) due to the second RAtransmission, the configuration time delay T_(act) _(_) _(PSCell) isexpressed as:

T _(act) _(_) _(PSCell) =β+T _(RRC) +T _(act)+_(SFNacq) +T _(act) _(_)_(PSCell) +T _(RA) _(_) _(PCell) *K,

wherein β is a margin parameter, T_(RRC) is a time delay due to a RRCprocedure, T_(act) is a time delay due to a second serving cellactivation procedure, _(SFNacq) is a time delay due to a SFN acquisitionprocedure, T_(act) _(_) _(PSCell) is a time delay due to the first RAtransmission, T_(RA) _(_) _(PCell) is a time delay due to the second RAtransmission and K is an integer defining the number of the second RAtransmissions to be sent while the wireless device 120 is preparing toperform or is performing configuration of the second serving cell 112 a.

Action 1004

In some embodiments, the wireless device 120 transmits the second RAtransmission to e.g. the first network node 111.

For example, this may be the case, when K is equal to or larger than 1.In such case, the wireless device 120 may transmit the second RAtransmission with priority over transmitting the first RA transmission.

The wireless device 120 may transmit the second RA transmission using anon-contention based Physical Radio Access Channel (PRACH).

Further, the wireless device 120 may transmit the second RA transmissionwhen required to be transmitted for performing or enabling one or moreof: a positioning measurement, a timing advance measurement, anactivation, an incoming call, a handover, and a cell change acquisitionof uplink transmit timing.

In some embodiments, the wireless device 120 transmits the second RAtransmission in dependence of a target configuration delay time for theconfiguration of the second serving cell 112 a.

FIG. 11 schematically illustrates another example of a method performedby a UE. A method in a UE, such as the wireless device 120, served bythe network node, such as the network node 111,112, may comprise theactions of:

-   -   determining (1101) whether the UE is triggered or has received a        request to send a second Random Access (RA) transmission while        the UE is preparing to perform or is performing configuration        and/or activation of at least one primary special cell (PSCell),        said second random access transmission is used for sending the        RA to a primary cell (PCell), and said PSCell and PCell are        primary serving cells belonging to Master or Main Cell Group        (MCG) and Secondary Cell Group (SCG) in DC operation. This        action may be performed by a determining module within the UE,        such as the wireless device 120.    -   adapting or selecting (1102) between at least a first method and        a second method to configure and/or activate at least one PSCell        depending upon the determination that whether or not the UE has        been triggered or received the request to send the second RA.        This action may be performed by an adapting or selecting module        within the UE, such as the wireless device 120.    -   configuring and/or activating (1103) at least one PSCell based        on the adapted method. This action may be performed by a        configuring and/or activating module within the UE, such as the        wireless device 120.

To perform the method for performing cell configuration, the wirelessdevice 120 may be configured according to an arrangement depicted inFIG. 12. As previously described, the wireless device 120 and the firstnetwork node 111 configured to serve the wireless device 120 areconfigured to operate in the wireless communications network 100.Further, the first network node 111 is configured to manage the firstserving cell 111 a.

The UE, e.g. the wireless device 120, may comprise an interface unit tofacilitate communications between the wireless device 120 and othernodes or devices, e.g. the network node 111,112. The interface may, forexample, include a transceiver configured to transmit and receive radiosignals over an air interface in accordance with a suitable standard. Insome embodiments, the wireless device 120 comprises an input and/oroutput interface 1200 configured to communicate with one or more networknodes, e.g. the first and second network nodes 111, 112. The inputand/or output interface 1200 may comprise a wireless receiver (notshown) and a wireless transmitter (not shown). Thus, the wireless device120 is configured to receive signals, data or information from the oneor more network nodes, e.g. the first and second network nodes 111, 112.Further, the wireless device 120 is configured to transmit signals, dataor information to the one or more network nodes, e.g. the first andsecond network nodes 111, 112.

In some embodiments, the wireless device 120 is configured to transmitthe second RA transmission to the first network node 111.

For example, when K is equal to or larger than 1, the wireless device120 is configured to transmit the second RA transmission with priorityover transmittal of the first RA transmission.

In some embodiments, the wireless device 120 is configured to transmitthe second RA transmission using a non-contention based Physical RadioAccess Channel (PRACH).

The wireless device 120 may further be configured to transmit the secondRA transmission when required to be transmitted for performing orenabling one or more of: a positioning measurement, a timing advancemeasurement, an activation, an incoming call, a handover, and a cellchange acquisition of uplink transmit timing.

In some embodiments, the wireless device 120 is configured to transmitthe second RA transmission in dependence of a target configuration delaytime for the configuration of the second serving cell 112 a.

The wireless device 120 may further be configured to determine, by meansof a determining module 1201 configured to determine, whether thewireless device 120 is required to send a second RA transmission. Thedetermining module 1201 may be implemented by or arranged incommunication with a processor 1205 of the wireless device 120. Theprocessor 1205 will be described in more detail below.

In some embodiments, the wireless device 120 is configured to determinewhether the wireless device 120 is required to send the second RAtransmission in the first serving cell 111 a to the first network node111 while performing configuration of the second serving cell 112 a.

The wireless device 120 may be configured to select, by means of aselecting module 1202 configured to select, configuration time delay.The selecting module 1202 may be implemented by or arranged incommunication with the processor 1205 of the wireless device 120.

In some embodiments, when the wireless device 120 is configured todetermine whether the wireless device 120 is required to send the secondRA transmission in the first serving cell 111 a to the first networknode 111 while performing configuration of the second serving cell 112a, the wireless device 120 is further configured to select betweenincluding and excluding the time delay T_(RA) _(_) _(PCell) due to thesecond RA transmission in the configuration time delay T_(act) _(_)_(PSCell) based on the determination.

As previously mentioned, when used herein, the expression “including andexcluding the time delay T_(RA) _(_) _(PCell) in the configuration timedelay T_(act) _(_) _(PSCell) ^(”) should be understood as whether or notthe time delay T_(RA) _(_) _(PCell) is to be comprised in theconfiguration time delay T_(act) _(_) _(PSCell). It should be understoodthat irrespective of whether or not the time delay T_(RA) _(_) _(PCell)is comprised in the configuration time delay T_(act) _(_) _(PSCell), theconfiguration time delay T_(act) _(_) _(PSCell) may comprise one or moreother time delays.

In some embodiments, the wireless device 120 is configured to selectbetween including and excluding the time delay T_(RA) _(_) _(PCell) dueto the second RA transmission by further being configured to select toexclude the time delay T_(RA) _(_) _(PCell) due to the second RAtransmission when the wireless device 120 is not required to send thesecond RA transmission to the first network node 111 while the wirelessdevice 120 is preparing to perform or is performing configuration of thesecond serving cell 112 a.

In some embodiments, when the wireless device 120 is configured toselect to exclude the time delay T_(RA) _(_) _(PCell) due to the secondRA transmission, the configuration time delay T_(act) _(_) _(PSCell) isexpressed as:

T _(act) _(_) _(PSCell) =α+T _(RRC) +T _(act) +T _(SFNacq) +T _(RA) _(_)_(PSCell),

wherein α is a margin parameter, T_(RRC) is a time delay due to a RRCprocedure, T_(act) is a time delay due to a second serving cellactivation procedure, T_(SFNacq) is a time delay due to a SFNacquisition procedure and T_(RA) _(_) _(PSCell) is a time delay due to afirst RA transmission in the second serving cell 112 a managed by thesecond network node 112.

Alternatively, in some embodiments, he wireless device 120 is configuredto select between including and excluding the time delay T_(RA) _(_)_(Peed) due to the second RA transmission by further being configured toselect to include the time delay T_(RA) _(_) _(PCell) due to the secondRA transmission when the wireless device 120 is to send the second RAtransmission to the first network node 111 while the wireless device 120is preparing to perform or is performing configuration of the secondserving cell 112 a.

In some embodiments, when the wireless device 120 is configured toselect include the time delay T_(RA) _(_) _(PCell) due to the second RAtransmission, the configuration time delay T_(act) _(_) _(PSCell) isexpressed as:

T _(act) _(_) _(PSCell) β+T _(RRC) +T _(act) +T _(SFNacq) +T _(RA) _(_)_(PSCell) +T _(RA) _(_) _(PCell) *K,

wherein β is a margin parameter, T_(RRC) is a time delay due to a RRCprocedure, T_(act) is a time delay due to a second serving cellactivation procedure, T_(SFNacq) is a time delay for a SFN acquisitionprocedure, T_(RA) _(_) _(PSCell) is a time delay due to the first RAtransmission, T_(RA) _(_) _(PCell) is a time delay due to the second RAtransmission and K is an integer defining the number of the second RAtransmissions to be sent while the wireless device 120 is preparing toperform or is performing configuration of the second serving cell 112 a.

The wireless device 120 is configured to configure, by means of aconfiguring module 1203 configured to configure, the second serving cell112 a as follows. The configuring module 1203 may be implemented by orarranged in communication with the processor 1205 of the wireless device120.

When the wireless device 120 is to send the second RA transmission inthe first serving cell 111 a to the first network node 111 whilepreparing to perform or performing configuration of the second servingcell 112 a managed by the second network node 112, the wireless device120 is configured to configure the second serving cell 112 a using aconfiguration time delay T_(act) _(_) _(PSCell) comprising at least atime delay T_(RA) _(_) _(PCell) due to the second RA transmission,otherwise the wireless device 120 is configured configure the secondserving cell 112 a using the configuration time delay T_(act) _(_)_(PSCell) excluding the time delay T_(RA) _(_) _(PCell) due to thesecond RA transmission.

In some embodiments, the configuration delay T_(act) _(_) _(PSCell)further comprises a time delay T_(RA) _(_) _(PSCell) due to a first RAtransmission in the second serving cell 112 a managed by the secondnetwork node 112.

In some embodiments, when the wireless device 120 is configured todetermine whether the wireless device 120 is required to send the secondRA transmission and configured to select between including and excludingthe time delay T_(RA) _(_) _(PCell) due to the second RA transmission,the wireless device 120 is configured to configure the second servingcell 112 a based on the selection.

The wireless device 120 may also comprise means for storing data. Insome embodiments, the wireless device 120 comprises a memory 1204configured to store the data. The data may be processed or non-processeddata and/or information relating thereto. The memory 1204 may compriseone or more memory units. Further, the memory 1204 may be a computerdata storage or a semiconductor memory such as a computer memory, aread-only memory, a volatile memory or a non-volatile memory. The memoryis arranged to be used to store obtained information, data,configurations, schedulings, and applications etc. to perform themethods herein when being executed in wireless device 120.

Embodiments herein for performing cell configuration may be implementedthrough one or more processors, such as the processor 1205 in thearrangement depicted in FIG. 12, together with computer program code forperforming the functions and/or method actions of embodiments herein.The program code mentioned above may also be provided as a computerprogram product, for instance in the form of a data carrier carryingcomputer program code for performing the embodiments herein when beingloaded into the wireless device 120. One such carrier may be in the formof an electronic signal, an optical signal, a radio signal or a computerreadable storage medium. The computer readable storage medium may be aCD ROM disc or a memory stick.

The computer program code may furthermore be provided as program codestored on a server and downloaded to the wireless device 120.

Those skilled in the art will also appreciate that the input/outputinterface 1200, the determining module 1201, the selecting module 1202,and the configuring module 1203 above may refer to a combination ofanalog and digital circuits, and/or one or more processors configuredwith software and/or firmware, e.g. stored in the memory 1204, that whenexecuted by the one or more processors such as the processors in thewireless device 120 perform as described above. One or more of theseprocessors, as well as the other digital hardware, may be included in asingle Application-Specific Integrated Circuitry (ASIC), or severalprocessors and various digital hardware may be distributed among severalseparate components, whether individually packaged or assembled into aSystem-on-a-Chip (SoC).

An example of a method performed by the first network node 111 forassisting a wireless device 120 in performing cell configuration willnow be described with reference to a flowchart depicted in FIG. 13. Aspreviously mentioned, the wireless device 120 and the first network node111 serving the wireless device 120 are operating in the wirelesscommunications network 100, and the first network node 111 manages thefirst serving cell 111 a.

The method comprises one or more of the following actions. It should beunderstood that actions may be taken in any suitable order and that someactions may be combined.

Action 1301

The first network node 111 determines based on one or more criteriawhether the wireless device 120 is using or is expected to use a firstmethod or a second method for performing configuration of a secondserving cell 112 a managed by a second network node 112.

This may also be expressed as the first network node 111 determinesbased on one or more criteria out of at least a first method and asecond method for use by a UE, e.g. the wireless device 120, toconfigure and/or activate at least one PSCell, e.g. the second servingcell 112 a. As will be described below, this action may be performed bya determining module within the network node such as the first networknode 111

The first method is configured to be performed over a configuration timedelay T_(act) _(_) _(PSCell) comprising at least a time delay T_(RA)_(_) _(PCell) due to a second RA transmission, when the wireless device120 is to send the second RA transmission in the first serving cell 111a to the first network node 111 while preparing to perform or performingconfiguration of the second serving cell 112 a.

The second method is configured to be performed over the configurationtime delay T_(RA) _(_) _(PSCell) excluding the time delay T_(RA) _(_)_(PCell) due to the second RA transmission, when the wireless device 120is not to send the second RA transmission in the first serving cell 111a while preparing to perform or performing configuration of the secondserving cell 112 a.

In some embodiments, the configuration time delay T_(act) _(_) _(PSCell)further comprises a time delay T_(RA) _(_) _(PSCell) due to a first RAtransmission in the second serving cell 112 a managed by the secondnetwork node 112.

Action 1302

The first network node 111 transmits, to the wireless device 120,information relating to the determined first or second method.

Thus, the first network node 111 may transmit to the UE, e.g. thewireless device 120, information related to the determined method and/orat least one parameter related to the to the determined method. As willbe described below, this action may be performed by a transmittingmodule within the network node such as the first network node 111.

In some embodiments, the information comprises one or more of: aparameter K defining the number of the second RA transmissions to besent while the wireless device 120 is preparing to perform or isperforming configuration of the second serving cell 112 a; an indicationwhether or not the wireless device 120 is allowed to transmit the secondRA transmission in the first serving cell 111 a while preparing toperform or performing configuration of the second serving cell 112 a;and a maximum allowed delay to perform the cell configuration.

To perform the method for assisting the wireless device 120 inperforming cell configuration, the first network node 111 may beconfigured according to an arrangement depicted in FIG. 14. Aspreviously described, the wireless device 120 and the first network node111 configured to serve the wireless device 120 are configured tooperate in the wireless communications network 100. Further, the firstnetwork node 111 is configured to manage the first serving cell 111 a.

The network node, e.g. the first network node 111, may comprise aninterface unit to facilitate communications between the network node andother nodes or devices, e.g. UE's such as the wireless device 120. Theinterface may, for example, include a transceiver configured to transmitand receive radio signals over an air interface in accordance with asuitable standard.

In some embodiments, the first network node 111 is configured toreceive, e.g. by means of a receiving module 1401 configured to receive,transmission from the wireless device 120. The receiving module 1401 maycomprise a wireless receiver.

The first network node 111 is configured to transmit, e.g. by means of atransmitting module 1402 configured to transmit, to the wireless device120, information relating to the determined first or second method. Thetransmitting module 1402 may comprise a wireless transmitter.

In some embodiments, the information comprises one or more of: aparameter K defining the number of the second RA transmissions to besent while the wireless device 120 is preparing to perform or isperforming configuration of the second serving cell 112 a; an indicationwhether or not the wireless device 120 is allowed to transmit the secondRA transmission in the first serving cell 111 a while preparing toperform or performing configuration of the second serving cell 112 a;and a maximum allowed delay to perform the cell configuration.

The first network node 111 is configured to determine, by means of adetermining module 1403 configured to determine, a method used by orexpected to be used by the wireless device 120 when performing cellconfiguration. The determining module 1403 may be implemented by orarranged in communication with a processor 1405 of the first networknode 111. The processor 1405 will be described in more detail below.

The first network node 111 is configured to determine based on one ormore criteria whether the wireless device 120 is using or is expected touse a first method or a 20 second method for performing configuration ofa second serving cell 112 a managed by a second network node 112.

As previously mentioned, the first method is configured to be performedover a configuration time delay T_(act) _(_) _(PSCell) comprising atleast a time delay T_(RA) _(_) _(PCell) due to a second Random Access,RA, transmission, when the wireless device 120 is to send the second RAtransmission in the first serving cell 111 a to the first network node111 while preparing to perform or performing configuration of the secondserving cell 112 a.

As also previously mentioned, the second method is configured to beperformed over the configuration time delay T_(act) _(_) _(PSCell)excluding the time delay T_(RA) _(_) _(PCell) due to the second RAtransmission, when the wireless device 120 is not to send the second RAtransmission in the first serving cell 111 a while preparing to performor performing configuration of the second serving cell 112 a.

In some embodiments, the configuration time delay T_(act) _(_) _(PSCell)further comprises a time delay T_(RA) _(_) _(PSCell) due to a first RAtransmission in the second serving cell 112 a managed by the secondnetwork node 112.

Embodiments herein for assisting a wireless device 120 in performingcell configuration may be implemented through one or more processors,such as the processor 1405 in the arrangement depicted in FIG. 14,together with computer program code for performing the functions and/ormethod actions of embodiments herein. The program code mentioned abovemay also be provided as a computer program product, for instance in theform of a data carrier carrying computer program code for performing theembodiments herein when being loaded into the first network node 111.One such carrier may be in the form of an electronic signal, an opticalsignal, a radio signal or a computer readable storage medium. Thecomputer readable storage medium may be a CD ROM disc or a memory stick.

The computer program code may furthermore be provided as program codestored on a server and downloaded to the first network node 111.

Those skilled in the art will also appreciate that receiving module1401, the transmitting module 1402, and the determining module 1403above may refer to a combination of analog and digital circuits, and/orone or more processors configured with software and/or firmware, e.g.stored in the memory 1404, that when executed by the one or moreprocessors such as the processors in the first network node 111 performas described above. One or more of these processors, as well as theother digital hardware, may be included in a single Application-SpecificIntegrated Circuitry (ASIC), or several processors and various digitalhardware may be distributed among several separate components, whetherindividually packaged or assembled into a System-on-a-Chip (SoC).

Exemplifying Embodiments

A method in the UE, e.g. the wireless device 120, of adapting PSCellconfiguration and/or activation procedure will now be described.

General Description of Adaptive Method

This embodiment discloses a method in a UE, e.g. the wireless device120, of adapting a procedure for performing PSCell, e.g. the secondserving cell 112 a, configuration and/or activation depending uponwhether the UE has been triggered to send random access on the PCell,e.g. the first serving cell 111 a, and at least one PSCell, e.g. thesecond serving cell 112 a. More specifically the UE, e.g. the wirelessdevice 120:

-   -   Uses a first method (aka first PSCell configuration and/or        activation method) to perform PSCell configuration and/or        activation provided that the UE is not triggered to        simultaneously perform random access (RA) on PCell (aka a first        RA) and RA on at least one PSCell (aka a second RA);    -   Uses a second method (aka second PSCell configuration and/or        activation method) to perform PSCell configuration and/or        activation provided that the UE is triggered to simultaneously        perform random access on PCell (i.e. first RA) and RA on at        least one PSCell (i.e. second RA).

Some actions that may be performed in the UE, e.g. the wireless device120, are as follows:

-   -   Determining that the UE is required to configure and/or activate        at least one PSCell.    -   Determining whether the UE is triggered or has received a        request to send a second RA (i.e. RA to PCell) while the UE is        preparing to perform or performing configuration and/or        activation of the at least one PSCell. This relates to Actions        1001 and 1101 previously described.    -   Adapting a method to configure and/or activate at least one        PSCell depending upon the determination that whether or not the        UE has been triggered or received send to send the second RA        e.g. adapting between the first and the second methods. This        relates to Actions 1002 and 1102 previously described.    -   Configuring and/or activating at least one PSCell based on the        adapted method. This relates to Actions 1003 and 1103 previously        described.

Some differences between the two methods are that:

-   -   The first method includes the time or delay due to RA        transmission to at least one PSCell (i.e. no delay due to RA to        PCell is included), and    -   The second method includes the times or delays due to: RA        transmission to at least one PSCell and one or more RA        transmissions to the PCell. Therefore the second method involves        additional delay due to at least one attempt of the second RA,

The use of the second method enables the UE to perform PSCellconfiguration and/or activation, which requires first RA as well executeprocedures which require the second RA. Therefore all procedures may beexecuted.

It is further described with specific examples below, that both methodsmay comprise additional delay components to account for the delay causedby other procedures such as RRC procedure etc.

The term ‘simultaneous triggering’, when used herein, means a situationin which the UE, e.g. the wireless device 120, may be triggered at thesame time, or within certain time period or when at least one randomaccess is in progress, to perform random access on the PCell, e.g. thefirst serving cell 111 a, and the at least one PSCell, e.g. the secondserving cell 112 a. This is explained with few exampled below:

-   -   In one example, the UE may receive the requests at exactly the        same time to send random access on PCell and at least one        PSCell.    -   In another example, the UE may receive two requests at different        times but within a time window (e.g. 5 subframes) while UE has        not yet starting sending the first random access based on the        first request.    -   In another example the UE may receive two requests at different        times such that the second request is received when UE has        already started sending the first random access based on the        first request/trigger.

The UE, e.g. the wireless device 120, may be triggered for sendingrandom access by a request received at the UE's physical layer from theUE's higher layer e.g. MAC layer protocol.

The term PSCell configuration means when the UE has at least acquiredtiming information of the PSCell e.g. synchronized to PSCell, acquiredits SFN etc.

The term PSCell activation means when the UE has acquired timinginformation of the PSCell and is also able to receive signals from thePSCell e.g. downlink control channel such as PDCCH, data channel such asPDSCH etc.

Examples of Adaptive PSCell Configuration and/or Activation Procedure

This section comprises some specific examples of adaptive PSCellconfiguration and/or activation procedure.

As an example:

-   -   The first method to perform PSCell configuration and/or        activation comprises the following individual procedures        performed by the UE, e.g. the wireless device 120:        -   RRC procedure to process the received message containing            PSCell configuration and/or activation command;        -   Procedure to acquire System Frame Number (SFN) of the            PSCell;        -   Activation procedure for PSCell;        -   Random Access (RA) procedure to send the first RA i.e. RA to            access PSCell.    -   The second method to perform PSCell configuration and/or        activation comprises the following individual procedures        performed by the UE, e.g. the wireless device 120:        -   RRC procedure to process the received message containing            PSCell configuration and/or activation command;        -   Procedure to acquire system frame number (SFN) of the            PSCell;        -   Activation procedure for PSCell;        -   Random access (RA) procedure to send the first RA i.e. RA to            access PSCell;        -   Random access (RA) procedure to send the second RA i.e. at            least one RA to access PCell;

In the above example the time to perform various procedures arerepresented as follows:

-   -   RRC procedure delay as T_(RRC);    -   PSCell activation procedure delay as T_(act);    -   SFN acquisition procedure delay as T_(SFNacq)    -   First RA procedure delay as T_(RA) _(_) _(PSCell)    -   Second RA procedure delay as T_(RA) _(_) _(PCell)

The total time or delay to perform PSCell configuration and/oractivation using the first method may be expressed by the followinggeneral expression:

T _(act) _(_) _(pscell) _(_) _(first) _(_) _(method) =g(α,T _(RRC) ,T_(act) ,T _(SFNacq) ,T _(RA) _(_) _(PSCell))  (1)

The total time in equation (1) may also be expressed using the followingspecific expression:

T _(act) _(_) _(pscell) _(_) _(first) _(_) _(method) =α+T _(RRC) +T_(act) +T _(SFNacq) +T _(RA) _(_) _(PSCell)  (2)

In equations (1) and (2), the parameter ‘a’ may account for a margin. Asa special case α=0, for example if no extra margin is needed or if it isincluded in other parameter.

The total time or delay to perform PSCell configuration and/oractivation using the second method may be expressed by the followinggeneral expression:

T _(act) _(_) _(pscell) _(_) _(second) _(_) _(method) =g(β,T _(RRC) ,T_(act) ,T _(SFNacq) ,T _(RA) _(_) _(PSCell) ,K)  (3)

The total time in equation (3) may also be expressed using the followingspecific expression:

T _(act) _(_) _(pscell) _(_) _(second) _(_) _(method) =β+T _(RRC) +T_(act) +T _(SFNacq) +T _(RA) _(_) _(PSCell) +T _(RA) _(_) _(PCell) *K  (4)

In equations (3)-(4) the parameter K is an integer and denotes thenumber of attempted PCell PRACH transmissions, i.e. the number of secondRA transmissions. The parameter K may be pre-defined, configured by thenetwork node, e.g. the first network node 111, or may be autonomouslyselected by the UE, e.g. the wireless device 120. As a special case K=1i.e. only one attempt to send the second RA to the PCell, e.g. the firstserving cell 111 a, while the PSCell, e.g. the second serving cell 112a, is being configured and/or activated. The use of the parameter K willbe further described below.

In equations (3) and (4), the parameter ‘13’ may account for a margin.As a special case β=0, for example if no extra margin is needed or if itis included in other parameter.

The expression in equation (4) enables the UE, i.e. when applying thesecond method, to first transmit the second RA to the PCell, e.g. thefirst serving cell 111 a, up to K times (depending on value of K) beforesending the second RA to the PSCell, second serving cell 112 a.Therefore the UE, e.g. the wireless device 120, performs the two typesof RA in tandem.

In any of the above expressions (1)-(4) any parameter other than T_(RA)_(_) _(PSCell) and T_(RA) _(_) _(PCell) may be set to zero. For exampleif UE knows the SFN of the PSCell then T_(SFNacq)=0.

In equations (1)-(4) the typical values of different procedures aredescribed below:

-   -   Typically the RRC procedure delay is about 15 ms.    -   The PSCell activation delay is in the order of 20 ms and 30 ms        if the PSCell, e.g. the second serving cell 112 a, is known and        unknown respectively. A PSCell is considered known if the UE,        e.g. the wireless device 120, is synchronized to the PSCell.        More specifically the PSCell is known if the UE has measured the        PSCell over the last certain time period; otherwise it is        considered unknown.    -   The SFN acquisition procedure for acquiring SFN of PSCell may        take about 50 ms. If the UE already knows the SFN then this time        may be much shorter or even set to 0 ms. For example if the        network node signals SFN of the PSCell then T_(SFNacq)=0 or        equal to a smaller value such as T_(SFNacq)=10 ms due to frame        timing uncertainty.    -   Each of the first and second RA procedures may require 20-50 ms        depending upon the configuration of the random access parameters        e.g. RA occasions, number of allowed retransmission attempts        etc.

The adaptive procedure to perform PSCell configuration and/or activationbased on equation (3) and (4) may be expressed as follows:

-   -   When the PSCell, e.g. the second serving cell 112 a, is being        configured and/or activated, if the UE, e.g. the wireless device        120, is not triggered perform simultaneous PRACH transmissions        to the PCell, e.g. the first serving cell 111 a, and to the        PSCell, e.g. the second serving cell 112 a, then the required        activation/configuration time for PSCell will be according to        the following expression based on the first method:

T _(act) _(_) _(pscell) =α+T _(RRC) +T _(act) +T _(SFNacq) +T _(RA) _(_)_(PSCell)

If there are situations when the UE, e.g. the wireless device 120, istriggered to perform simultaneous PRACH transmissions to both the PCell,e.g. the first serving cell 111 a, and the PSCell, e.g. the secondserving cell 112 a, then the activation/configuration time required forPSCell will be according to the following expression based on the secondmethod:

T _(act) _(_) _(pscell) =T _(RRC) +T _(act) +T _(SFNacq) +T _(RA) _(_)_(PSCell) T _(RA) _(_) _(PCell) *K

The K may also have a default value e.g. K=1. That is when only certainnumber of second RA transmissions while the PSCell, e.g. the secondserving cell 112 a, is configured and/or activated is pre-defined.

The chosen value of K, which is an integer, gives rise to differentrules or schemes, which are described in the coming sections.

Method of Prioritizing Between PSCell and PCell PRACH Transmissions

In some embodiments, the UE, e.g. the wireless device 120, may betriggered to use one of the following rules while configuring and/oractivating the PSCell, e.g. the second serving cell 112 a:

-   -   1 Discard the second RA transmission if it occurs while the        PSCell is being configured and/or activated i.e. K=0;    -   2 Prioritize the second RA transmission over the first RA        transmission i.e. K≧1;    -   3 Prioritize the second RA transmission over the first RA        transmission for up to certain number of the second RA        transmissions, and discard beyond that number i.e. 1≦K≦m. The        value of m may be pre-defined, configured by the network node,        e.g. the first network node 111, or selected by the UE, e.g. the        wireless device 120, autonomously.

The UE, e.g. the wireless device 120, may be triggered to configureand/or activate the PSCell, e.g. the second serving cell 112 a,according to any of above principle based on:

-   -   Pre-defined rule;    -   Information received from the network node, e.g. the first        network node 111 a, e.g. value of K is signalled;    -   UE autonomously selection e.g. UE selects the value of K

In case of autonomous selection of the rule, the UE, e.g. the wirelessdevice 120, may also inform the network node, e.g. the first networknode 111, as to which of the rule has been used by the UE e.g. have setK=0 as in rule #1.

Furthermore, the one or more criterions may be used to define which ofthe above rules is to be used by the UE in case both the first and thesecond RA are triggered by the UE during the PSCell configuration and/oractivation procedure.

As an example embodiment, the UE may autonomously set K=0, i.e. applyrule #1 above, based on certain criterion. Several examples of criteriafor selecting the rule are described below.

Prioritization Based on Whether RACH is Contention Based onNon-Contention Based

In one aspect of some embodiments, the UE, e.g. the wireless device 120,may transmit PRACH to the PCell, e.g. the first serving cell 111 a, onlyif the PRACH is non-contention based. For example, the UE may use thesecond method, e.g. expressions (3)-(4); if the UE is triggered to sendthe second RA using non-contention based principle e.g. for performinghandover. Therefore, UE may use rule #1 or rule #2. In case of rule #2the UE may also use certain maximum value of K e.g. K=4.

Prioritization Based on Purpose of PRACH to PCell.

In another aspect of some embodiments, the UE, e.g. the wireless device120, may transmit PRACH to the PCell, e.g. the first serving cell 111 a,depending on the purpose of the RACH. For example, the UE may send thePRACH to the PCell only when the PRACH is triggered to be transmittedfor certain tasks or purposes. Examples of use cases of RA are for:positing measurement, timing advance, activation, incoming call,handover, cell change, acquisition of UL transmit timing, etc.

For example for certain critical tasks, e.g. second RA transmission fordoing or enabling positioning measurements and/or handover; it may bepre-defined that the UE shall use at least rule #2 or UE may beconfigured to use rule #2 by the network node, e.g. the first networknode 111.

Target Delay of PSCell Configuration and/or Activation Procedure

In another aspect of some embodiments, the UE, e.g. the wireless device120, may be required to transmit PRACH to the PCell, e.g. the firstserving cell 111 a, depending on the target delay of the PSCellconfiguration and/or activation procedure. For example, the maximumallowed delay may be pre-defined or configured by the network node, e.g.the first network node 111.

If the UE cannot perform the PSCell configuration and/or activationprocedure with the target delay, then the UE may set K=0. Otherwise, theUE may choose the maximum value of K provided the PSCell configurationand/or activation procedure can be done within the target delay.

As previously described, the embodiments herein may be implementedthrough one or more processors, such as a processor in the UE 120depicted in FIG. 11, and a processor in the network node 111,112depicted in FIG. 13, together with computer program code for performingthe functions and actions of the embodiments herein. The program codementioned above may also be provided as a computer program product, forinstance in the form of a data carrier carrying computer program codefor performing the embodiments herein when being loaded into the in thenetwork node 111,112 or the UE 120. One such carrier may be in the formof a CD ROM disc. It is however feasible with other data carriers suchas a memory stick. The computer program code may furthermore be providedas pure program code on a server and downloaded to the network node111,112 or the UE 120.

The network node 111,112 and the UE 120 may further comprise a memorycomprising one or more memory units. The memory is arranged to be usedto store obtained information, store data, configurations, scheduling,and applications etc. to perform the methods herein when being executedin the network node 111,112 or the UE 120.

Those skilled in the art will also appreciate that the determiningmodule, adapting module, selecting module, configuring module,activating module, transmitting module, receiving module, sending moduleand performing module described above may refer to a combination ofanalog and digital circuits, and/or one or more processors configuredwith software and/or firmware, e.g. stored in the memory, that whenexecuted by the one or more processors such as the processors in thenetwork node 111,112 and UE 120 perform as described above. One or moreof these processors, as well as the other digital hardware, may beincluded in a single application-specific integrated circuitry (ASIC),or several processors and various digital hardware may be distributedamong several separate components, whether individually packaged orassembled into a system-on-a-chip (SoC).

When the word “comprise” or “comprising” is used in this disclosure itshall be interpreted as non-limiting, i.e. meaning “consist at leastof”.

The embodiments herein are not limited to the above described preferredembodiments. Various alternatives, modifications and equivalents may beused.

Therefore, the above embodiments should not be taken as limiting thescope of the invention, which is defined by the appending claims.

ABBREVIATIONS

-   -   MeNB Master eNode B    -   SeNB Secondary eNode B    -   PSCell Primary SCell    -   PCC Primary component carrier    -   PCI Physical cell identity    -   PSS Primary synchronization signal    -   RAT Radio Access Technology    -   RRC Radio resource control    -   RSCP Received signal code power    -   RSRP Reference Signal Received Power    -   RSRQ Reference Signal Received Quality    -   RSSI Received signal strength indication    -   SCC Secondary component carrier    -   SIB System information block    -   SON Self-organizing networks    -   SSS Secondary synchronization signal    -   TDD Time division duplex    -   UARFCN UMTS Absolute Radio Frequency Channel Number    -   HO Handover    -   UE User equipment    -   RNC Radio Network Controller    -   BSC Base station Controller    -   PCell Primary Cell    -   SCell Secondary Cell

1. A method performed by a wireless device for performing cellconfiguration, wherein the wireless device and a first network nodeserving the wireless device are operating in a wireless communicationsnetwork, wherein the first network node manages a first serving cell,and wherein the method comprises: when the wireless device is to send asecond Random Access, RA, transmission in the first serving cell to thefirst network node while preparing to perform or performingconfiguration of a second serving cell managed by a second network node,configuring the second serving cell using a configuration time delayTact_PSCell comprising at least a time delay TRA_PCell due to the secondRA transmission; otherwise configuring the second serving cell using theconfiguration time delay Tact_PSCell excluding the time delay TRA_PCelldue to the second RA transmission.
 2. The method of claim 1, wherein theconfiguration delay Tact_PSCell further comprises a time delayTRA_PSCell due to a first RA transmission in the second serving cellmanaged by the second network node.
 3. The method of claim 1, furthercomprising: determining whether the wireless device is required to sendthe second RA transmission in the first serving cell to the firstnetwork node while performing configuration of the second serving cell;selecting between including and excluding the time delay TRA_PCell dueto the second RA transmission in the configuration time delayTact_PSCell based on the determination; and configuring the secondserving cell based on the selection.
 4. The method of claim 3, whereinselecting between including and excluding the time delay TRA_PCell dueto the second RA transmission further comprises: selecting to excludethe time delay TRA_PCell due to the second RA transmission when thewireless device is not required to send the second RA transmission tothe first network node while the wireless device is preparing to performor is performing configuration of the second serving cell.
 5. The methodof claim 4, wherein the configuration time delay Tact_PSCell isexpressed as:Tact_PSCell=α+TRRC+Tact+TSFNacq+TRA_PSCell, wherein α is a marginparameter, TRRC is a time delay due to a Radio Resource Control RRC,procedure, Tact is a time delay due to a second serving cell activationprocedure, TSFNacq is a time delay due to a System Frame Number, SFN,acquisition procedure and TRA_PSCell is a time delay due to a first RAtransmission in the second serving cell managed by the second networknode.
 6. The method of claim 3, wherein selecting between including andexcluding the time delay TRA_PCell due to the second RA transmissionfurther comprises: selecting to include the time delay TRA_PCell due tothe second RA transmission when the wireless device is to send thesecond RA transmission to the first network node while the wirelessdevice is preparing to perform or is performing configuration of thesecond serving cell.
 7. The method of claim 6, wherein the configurationtime delay Tact_PSCell is expressed as:Tact_PSCell=β+TRRC+Tact+TSFNacq+TRA_PSCell+TRA_PCell*K, wherein β is amargin parameter, TRRC is a time delay due to a RRC procedure, Tact is atime delay due to a second serving cell activation procedure, TSFNacq isa time delay due to a SFN acquisition procedure, TRA_PSCell is a timedelay due to the first RA transmission, TRA_PCell is a time delay due tothe second RA transmission and K is an integer defining the number ofthe second RA transmissions to be sent while the wireless device ispreparing to perform or is performing configuration of the secondserving cell.
 8. The method of claim 7, further comprising: when K isequal to or larger than 1, transmitting the second RA transmission withpriority over transmitting the first RA transmission.
 9. The method ofclaim 6, further comprising: transmitting the second RA transmissionusing a non-contention based Physical Radio Access Channel, PRACH. 10.The method of claim 6, further comprising: transmitting the second RAtransmission when required to be transmitted for performing or enablingone or more of: a positioning measurement, a timing advance measurement,an activation, an incoming call, a handover, and a cell changeacquisition of uplink transmit timing.
 11. The method of claim 6,further comprising: transmitting the second RA transmission independence of a target configuration delay time for the configuration ofthe second serving cell.
 12. A wireless device for performing cellconfiguration, wherein the wireless device and a first network nodeserving the wireless device are operable in a wireless communicationsnetwork, wherein the first network node manages a first serving cell,and wherein the wireless device is configured to: when the wirelessdevice is to send a second Random Access, RA, transmission in the firstserving cell to the first network node while preparing to perform orperforming configuration of a second serving cell managed by a secondnetwork node, configure the second serving cell using a configurationtime delay Tact_PSCell comprising at least a time delay TRA_PCell due tothe second RA transmission, otherwise configure the second serving cellusing the configuration time delay Tact_PSCell excluding the time delayTRA_PCell due to the second RA transmission.
 13. The wireless device ofclaim 12, wherein the configuration delay Tact_PSCell further comprisesa time delay TRA_PSCell due to a first RA transmission in the secondserving cell managed by the second network node.
 14. The wireless deviceof claim 12, further being configured to: determine whether the wirelessdevice is required to send the second RA transmission in the firstserving cell to the first network node while performing configuration ofthe second serving cell; select between including and excluding the timedelay TRA_PCell due to the second RA transmission in the configurationtime delay Tact_PSCell based on the determination; and configure thesecond serving cell based on the selection.
 15. The wireless device ofclaim 14, wherein the wireless device is configured to select betweenincluding and excluding the time delay TRA_PCell due to the second RAtransmission by further being configured to: select to exclude the timedelay TRA_PCell due to the second RA transmission when the wirelessdevice is not required to send the second RA transmission to the firstnetwork node while the wireless device is preparing to perform or isperforming configuration of the second serving cell.
 16. The wirelessdevice of claim 15, wherein the configuration time delay Tact_PSCell isexpressed as:Tact_PSCell=α+TRRC+Tact+TSFNacq+TRA_PSCell, wherein α is a marginparameter, TRRC is a time delay due to a Radio Resource Control RRC,procedure, Tact is a time delay due to a second serving cell activationprocedure, TSFNacq is a time delay due to a System Frame Number, SFN,acquisition procedure and TRA_PSCell is a time delay due to a first RAtransmission in the second serving cell managed by the second networknode.
 17. The wireless device of claim 14, wherein the wireless deviceis configured to select between including and excluding the time delayTRA_PCell due to the second RA transmission by further being configuredto: select to include the time delay TRA_PCell due to the second RAtransmission when the wireless device is to send the second RAtransmission to the first network node while the wireless device ispreparing to perform or is performing configuration of the secondserving cell.
 18. The wireless device of claim 17, wherein theconfiguration time delay Tact_PSCell is expressed as:Tact_PSCell=β+TRRC+Tact+TSFNacq+TRA_PSCell+TRA_PCell*K, wherein β is amargin parameter, TRRC is a time delay due to a RRC procedure, Tact is atime delay due to a second serving cell activation procedure, TSFNacq isa time delay for a SFN acquisition procedure, TRA_PSCell is a time delaydue to the first RA transmission, TRA_PCell is a time delay due to thesecond RA transmission and K is an integer defining the number of thesecond RA transmissions to be sent while the wireless device ispreparing to perform or is performing configuration of the secondserving cell.
 19. The wireless device of claim 18, further beingconfigured to: when K is equal to or larger than 1, transmit the secondRA transmission with priority over transmittal of the first RAtransmission.
 20. The wireless device of claim 17, further beingconfigured to: transmit the second RA transmission using anon-contention based Physical Radio Access Channel, PRACH.
 21. Thewireless device of claim 17, further being configured to: transmit thesecond RA transmission when required to be transmitted for performing orenabling one or more of: a positioning measurement, a timing advancemeasurement, an activation, an incoming call, a handover, and a cellchange acquisition of uplink transmit timing.
 22. The wireless device ofclaim 17, further being configured to: transmit the second RAtransmission in dependence of a target configuration delay time for theconfiguration of the second serving cell.
 23. A method performed by afirst network node for assisting a wireless device in performing cellconfiguration, wherein the wireless device and the first network nodeserving the wireless device are operating in a wireless communicationsnetwork, wherein the first network node manages a first serving cell,and wherein the method comprises: determining based on one or morecriteria whether the wireless device is using or is expected to use afirst method or a second method for performing configuration of a secondserving cell managed by a second network node, wherein the first methodis configured to be performed over a configuration time delayTact_PSCell comprising at least a time delay TRA_PCell due to a secondRandom Access, RA, transmission, when the wireless device is to send thesecond RA transmission in the first serving cell to the first networknode while preparing to perform or performing configuration of thesecond serving cell, and wherein the second method is configured to beperformed over the configuration time delay TRA_PSCell excluding thetime delay TRA_PCell due to the second RA transmission, when thewireless device is not to send the second RA transmission in the firstserving cell while preparing to perform or performing configuration ofthe second serving cell; and transmitting, to the wireless device,information relating to the determined first or second method.
 24. Themethod of claim 23, wherein the information comprises one or more of: aparameter K defining the number of the second RA transmissions to besent while the wireless device is preparing to perform or is performingconfiguration of the second serving cell; an indication whether or notthe wireless device is allowed to transmit the second RA transmission inthe first serving cell while preparing to perform or performingconfiguration of the second serving cell; and a maximum allowed delay toperform the cell configuration.
 25. The method of claim 23, wherein theconfiguration time delay Tact_PSCell further comprises a time delayTRA_PSCell due to a first RA transmission in the second serving cellmanaged by the second network node.
 26. A first network node forassisting a wireless device in performing cell configuration, whereinthe wireless device and the first network node serving the wirelessdevice are operable in a wireless communications network, wherein thefirst network node manages a first serving cell, and wherein the firstnetwork node is configured to: determine based on one or more criteriawhether the wireless device is using or is expected to use a firstmethod or a second method for performing configuration of a secondserving cell managed by a second network node, wherein the first methodis configured to be performed over a configuration time delayTact_PSCell comprising at least a time delay TRA_PCell due to a secondRandom Access, RA, transmission, when the wireless device is to send thesecond RA transmission in the first serving cell to the first networknode while preparing to perform or performing configuration of thesecond serving cell, and wherein the second method is configured to beperformed over the configuration time delay Tact_PSCell excluding thetime delay TRA_PCell due to the second RA transmission, when thewireless device is not to send the second RA transmission in the firstserving cell while preparing to perform or performing configuration ofthe second serving cell; and transmit, to the wireless device,information relating to the determined first or second method.
 27. Thefirst network node of claim 26, wherein the information comprises one ormore of: a parameter K defining the number of the second RAtransmissions to be sent while the wireless device is preparing toperform or is performing configuration of the second serving cell; anindication whether or not the wireless device is allowed to transmit thesecond RA transmission in the first serving cell while preparing toperform or performing configuration of the second serving cell; and amaximum allowed delay to perform the cell configuration.
 28. The firstnetwork node of claim 26, wherein the configuration time delayTact_PSCell further comprises a time delay TRA_PSCell due to a first RAtransmission in the second serving cell managed by the second networknode.
 29. A computer program, comprising instructions which, whenexecuted on at least one processor, causes the at least one processor tocarry out the method according to claim
 1. 30. A non-transitory computerreadable storage medium comprising the computer program of claim 29.